1. Field of Invention
The present invention relates to a pipe and, more particularly, to an axially expansible pipe assembly.
2. Related Prior Art
A conventional pipe assembly includes an internal pipe inserted in an external pipe. The internal pipe is expansible while the external pipe is not. The external diameter of the internal pipe is smaller than the internal diameter of the external pipe when the internal pipe is not expanded. Hence, there is a gap between the internal and external pipes. The gap allows the internal pipe to expand when the internal pipe is filled with water. The expansion of the internal pipe in the radial direction suppresses the expansion of the internal pipe in the axial direction. The length of the internal pipe is smaller than that of the external pipe when the internal pipe is not expanded. When the internal pipe is not expanded, there are inevitably wrinkles on the external pipe because the external pipe does not shrink. The wrinkles render the conventional pipe assembly aesthetically unpleasant. Moreover, it is difficult to turn the pipe assembly into a roll. The internal pipe becomes too thin to survive high hydraulic pressure when it is filled with water.
Therefore, the present invention is intended to obviate or at least alleviate the problems encountered in prior art.